Biohacking Glossary

Activated Charcoal

Also: Activated carbon, Medicinal charcoal

Carbon processed at high temperatures to create a highly porous surface with enormous adsorptive capacity (~1,000 m² per gram). Binds toxins, drugs, and gases in the gastrointestinal tract, preventing absorption. Used clinically for acute poisoning and by biohackers for binding dietary mycotoxins, endotoxins, and food-derived toxins. Must be taken away from medications and supplements.

Adaptogen

A class of herbs and mushrooms that help the body resist physical, chemical, and biological stressors. Examples include ashwagandha (KSM-66), rhodiola rosea, ginseng, lion's mane, reishi, and cordyceps. Primarily act on the HPA axis to modulate cortisol.

Akkermansia muciniphila

Also: Akkermansia

A mucus-degrading gut bacterium that constitutes 1–3% of the gut microbiome in healthy adults and is inversely correlated with obesity, diabetes, and metabolic syndrome. It strengthens the mucus layer, reduces intestinal permeability, and improves glucose homeostasis. Depleted by processed food, antibiotics, and sedentary lifestyle.

Ashwagandha (KSM-66)

An adaptogenic herb (Withania somnifera) extensively studied for reducing cortisol, improving stress resilience, enhancing testosterone, improving sleep quality, and boosting endurance. KSM-66 is the most clinically studied root extract form.

Autophagy

Also: Cellular self-digestion

A cellular self-cleaning process in which the body breaks down and recycles damaged or dysfunctional cell components. Activated by fasting, caloric restriction, and exercise, autophagy is associated with longevity, reduced inflammation, and cancer prevention.

BDNF (Brain-Derived Neurotrophic Factor)

A protein that supports the survival of existing neurons and encourages the growth of new neurons and synapses. Often called 'Miracle-Gro for the brain.' Exercise, cold exposure, intermittent fasting, and certain nootropics increase BDNF levels.

Berberine

A plant alkaloid (from goldenseal, barberry) with potent AMPK-activating effects similar to metformin. Used to improve insulin sensitivity, lower blood glucose, support gut health, and as a potential longevity compound.

Biofeedback

A technique using electronic monitoring to train individuals to gain voluntary control over involuntary physiological functions (heart rate, muscle tension, skin conductance, brainwaves). Used for stress management, performance enhancement, and pain reduction.

Biohacking

Also: Human optimization, self-experimentation

The practice of using science, technology, and self-experimentation to optimize biology — especially one's own. Biohacking spans a wide spectrum: from lifestyle optimization (nutrition, sleep, cold exposure, breathwork) to wearables and data tracking, supplementation and nootropics, to more extreme frontiers like DIY genetics, peptide therapy, and body augmentation. The goal is to take an active, evidence-informed role in optimizing human performance, health, and longevity rather than leaving it to chance or conventional medicine alone.

Biological Age

A measure of how old a person's body is physiologically, as opposed to chronological age. Can be estimated via epigenetic clocks, telomere length, organ function tests, and biomarker panels. Biohackers aim to reduce biological age below chronological age.

Blue Light Blocking

The practice of filtering or avoiding blue-wavelength light (400–490 nm) emitted by screens and LED lighting in the evening, as blue light suppresses melatonin production and delays circadian phase. Tools include blue-light-blocking glasses, night mode apps, and amber lighting.

Brainwave Entrainment

Also: Binaural beats

The practice of using external auditory (binaural beats, isochronic tones) or visual stimuli to synchronize brainwave frequencies to a desired state — alpha (relaxed focus), theta (creativity/meditation), delta (deep sleep), or gamma (high cognition).

Breathwork

Conscious manipulation of breathing patterns to influence physiological and psychological states. Protocols include the Wim Hof Method (hyperventilation + breath holds), box breathing (4-4-4-4), and 4-7-8 breathing. Affects HRV, CO2 tolerance, stress response, and focus.

Butyrate

The most important short-chain fatty acid for colon health. Produced by bacterial fermentation of fibre (especially from resistant starch, oats, and legumes), butyrate fuels intestinal epithelial cells, tightens tight-junction proteins to reduce leaky gut, exerts anti-cancer properties, and suppresses inflammatory pathways.

Caloric Restriction (CR)

Reducing total daily caloric intake (typically by 20–40%) without malnutrition. One of the most robust interventions for extending lifespan in animal studies. Activates AMPK and sirtuins, reduces IGF-1, and promotes autophagy.

Chlorella

A single-celled green freshwater algae rich in chlorophyll, vitamins, and minerals. The cell wall of cracked-cell chlorella binds to heavy metals (mercury, lead, cadmium) and pesticides in the GI tract, supporting fecal excretion before reabsorption. Also used as a food supplement for immune support and GABA production.

Circadian Rhythm

The body's internal 24-hour biological clock regulating sleep-wake cycles, hormone release, body temperature, and metabolism. Disruptions (jet lag, shift work, artificial light) are linked to obesity, diabetes, and cognitive decline. Biohackers optimize light exposure, meal timing, and temperature to align circadian rhythms.

Citizen Science

Scientific research conducted wholly or partially by amateur or non-professional scientists. In biohacking, it refers to self-experimentation and community-driven research that contributes data outside formal academic institutions.

Cold Exposure / Cold Thermogenesis

Deliberate exposure to cold temperatures (ice baths, cold showers, cryotherapy) to activate brown adipose tissue, increase norepinephrine, improve recovery, reduce inflammation, and potentially boost metabolism. Popularized by Wim Hof and Andrew Huberman.

Continuous Glucose Monitor (CGM)

A wearable device that measures interstitial glucose levels in real time, typically every 5–15 minutes. Used by diabetics and biohackers alike to understand how food, exercise, stress, and sleep affect blood sugar levels and optimize metabolic health.

CoQ10 (Coenzyme Q10)

A fat-soluble compound essential for mitochondrial ATP production and as a powerful antioxidant. Levels decline with age and are depleted by statin drugs. Supplemented in ubiquinone or the more bioavailable ubiquinol form.

Cortisol

The primary stress hormone released by the adrenal glands in response to stress or low blood glucose. In acute situations it mobilizes energy; chronic elevation suppresses immunity, impairs cognition, disrupts sleep, and promotes fat storage around the abdomen.

CRISPR-Cas9

A revolutionary gene-editing tool derived from a bacterial immune system that allows precise modification of DNA sequences. Used in medical research and, controversially, by some DIY biohackers attempting self-experimentation with gene editing.

DIY Biology (Garage Biology)

A movement in which non-professional scientists conduct biological experiments outside traditional laboratory settings using consumer-grade equipment. Ranges from hobbyist microbiology to serious citizen science and citizen biomedical research.

DNA Methylation

The addition of a methyl group to a DNA base (usually cytosine), which typically silences gene expression. DNA methylation patterns change with age and are used as the basis for epigenetic clocks. Diet (folate, B12, SAM-e) influences methylation.

Dopamine

A neurotransmitter central to reward, motivation, movement, and focus. Biohackers optimize dopamine through cold exposure, exercise, music, tyrosine-rich foods, and avoiding dopamine-depleting behaviors (excessive social media, junk food).

Dry Fasting

An extreme fasting practice that restricts both food and water intake for a defined period. Claimed to accelerate autophagy and detoxification more than water fasting, but carries significant risks of dehydration, kidney damage, and electrolyte imbalance. Not recommended without medical supervision.

Dysbiosis

An imbalance in the gut microbial community characterized by reduced diversity, decreased beneficial bacteria, or overgrowth of harmful species. Associated with IBS, obesity, autoimmune disorders, depression, and metabolic syndrome.

EEG (Electroencephalography)

A method of measuring electrical activity in the brain via electrodes placed on the scalp. Used in biohacking for neurofeedback training, sleep stage tracking, and real-time brainwave monitoring. Consumer devices include Muse and NeuroSky.

Enteric Nervous System

Also: Second brain, ENS

A network of approximately 500 million neurons embedded in the gastrointestinal tract wall — often called the 'second brain.' It operates independently of the central nervous system, regulating gut motility, secretion, and blood flow. Communicates bidirectionally with the brain via the vagus nerve as part of the gut-brain axis.

Epigenetic Clock

A biological age measurement tool based on DNA methylation patterns at specific genomic sites. Epigenetic clocks (Horvath clock, GrimAge, DunedinPACE) can predict mortality risk and measure the effectiveness of anti-aging interventions.

Epigenetics

The study of heritable changes in gene expression that do not involve changes to the DNA sequence itself. Epigenetic modifications (DNA methylation, histone modification) are influenced by diet, stress, exercise, and environmental exposures — and can be reversed.

EPOC (Excess Post-Exercise Oxygen Consumption)

Elevated oxygen consumption and metabolic rate following intense exercise — the 'afterburn effect.' The body burns additional calories restoring oxygen stores, removing lactate, and repairing muscle tissue after high-intensity workouts.

Fisetin

A flavonoid senolytic found in strawberries, apples, and persimmons that selectively clears senescent cells. Animal studies show significant lifespan extension. Used by longevity biohackers in periodic high-dose protocols (e.g., 20 mg/kg for 2 days/month).

Floatation Tank (Sensory Deprivation)

Also: REST (Restricted Environmental Stimulation Therapy)

A soundproof, lightproof tank filled with body-temperature salt water allowing effortless floating. Eliminates external sensory input to promote deep relaxation, reduce cortisol, alleviate pain, and enhance creativity and meditative states.

Flow State

A mental state of complete absorption and energized focus in an activity, often described as being 'in the zone.' Associated with peak performance, creativity, and subjective well-being. Biohackers use techniques like neurofeedback, meditation, and nootropics to induce flow states.

Glucose Optimization

Strategies to maintain stable blood glucose levels, minimizing spikes and crashes. Includes dietary choices (low glycemic index foods), meal sequencing (fiber and protein before carbs), exercise timing, and continuous glucose monitoring (CGM).

Glutathione

Also: GSH, Master antioxidant

The body's most abundant endogenous antioxidant and master detoxifier — a tripeptide of glutamate, cysteine, and glycine. Acts as a direct scavenger of reactive oxygen species and is the primary co-substrate for Phase II GST conjugation. Levels decline with age, chronic illness, and toxic load. Boosted by NAC, glycine, alpha-lipoic acid, and liposomal glutathione supplements.

Glycemic Index (GI)

A ranking system (0–100) measuring how quickly a carbohydrate-containing food raises blood glucose compared to pure glucose. Low-GI foods (≤55) cause slower, more gradual glucose rises. Used in biohacking to optimize energy, mood, and metabolic health.

Grinders

A community of biohackers who augment their bodies with technology — typically implanting electronic devices under the skin to add new senses, capabilities, or data interfaces. Examples include NFC/RFID implants, magnetic fingertip implants, and LED subdermal implants.

Grounding (Earthing)

Direct physical contact between the human body and the Earth's surface (barefoot on grass, soil, sand, or water). Proponents claim it reduces inflammation and cortisol by allowing electron transfer from the Earth's surface to the body.

Gut Microbiome

The complex community of trillions of microorganisms (bacteria, viruses, fungi, archaea) residing in the gastrointestinal tract. The microbiome influences digestion, immune function, mood (gut-brain axis), metabolism, and disease risk. Diversity is generally associated with better health.

Gut-Brain Axis

The bidirectional communication network between the gut microbiome and the central nervous system via the vagus nerve, immune system, and neuroendocrine pathways. The gut produces ~90% of the body's serotonin and directly influences mood, cognition, and behavior.

Heart Rate Variability (HRV)

The variation in time between consecutive heartbeats. High HRV indicates greater autonomic nervous system flexibility and recovery capacity; low HRV correlates with stress, overtraining, and illness. Measured by wearables like WHOOP, Oura Ring, and Garmin.

Heavy Metal Detox

Also: Chelation therapy, Heavy metal chelation

Protocols aimed at reducing body burden of toxic heavy metals — mercury, lead, arsenic, cadmium, and aluminium. Clinical approaches use pharmaceutical chelators (DMSA, DMPS, EDTA) under medical supervision. Biohacker approaches include chlorella, cilantro, modified citrus pectin, and zeolite clay as gentler binding agents. Testing via DMPS provocation urine tests or hair mineral analysis.

HIIT (High-Intensity Interval Training)

A training protocol alternating short bursts of maximum-effort exercise with brief recovery periods. Shown to improve VO2 max, insulin sensitivity, and fat oxidation in less time than steady-state cardio. Produces a significant EPOC (afterburn) effect.

Hormesis

A biological phenomenon where exposure to low doses of a stressor produces beneficial adaptive responses, while high doses are harmful. Exercise, cold exposure, fasting, and mild heat stress are examples of hormetic stressors that enhance resilience and longevity.

Human Growth Hormone (HGH)

A hormone secreted by the pituitary gland that stimulates growth, cell reproduction, and regeneration. Peaks during deep sleep and after intense exercise. Biohackers optimize it via sleep quality, sauna use, fasting, and sometimes peptide secretagogues.

Implantable Biochip

A small electronic device implanted under the skin that can store data, enable NFC communication, or monitor biological parameters. Grinder biohackers implant RFID/NFC chips for keyless entry or data storage.

Infrared Sauna Therapy

Also: IR sauna, Far-infrared sauna (FIR)

Use of infrared light (near-, mid-, or far-infrared wavelengths) to heat the body from within, producing deep sweating at lower ambient temperatures than traditional saunas (45–60°C vs. 80–100°C). Sweat from infrared sauna sessions has been shown to contain heavy metals (lead, mercury, cadmium), BPA, and phthalates in measurable concentrations. Also used for cardiovascular conditioning, muscle recovery, and pain relief.

Insulin Sensitivity

The degree to which cells respond efficiently to insulin's signal to take up glucose from the blood. High insulin sensitivity (good) means less insulin is needed. Poor insulin sensitivity (insulin resistance) drives type 2 diabetes, obesity, and metabolic syndrome.

Intermittent Fasting (IF)

Also: Time-Restricted Eating (TRE)

An eating pattern that alternates between periods of eating and fasting. Common protocols include 16:8 (16 hours fasting, 8-hour eating window), 5:2 (normal eating 5 days, restricted calories 2 days), and OMAD (One Meal A Day). Associated with weight management, improved insulin sensitivity, and autophagy induction.

Ketogenic Diet

Also: Keto diet

A high-fat, moderate-protein, very low-carbohydrate diet (typically <50g carbs/day) that forces the body into ketosis. Used therapeutically for epilepsy and increasingly adopted by biohackers for cognitive enhancement, weight loss, and metabolic health.

Ketosis

A metabolic state in which the body burns fat as its primary fuel source instead of glucose, producing ketone bodies (acetoacetate, beta-hydroxybutyrate, acetone). Achieved through a ketogenic diet (high fat, very low carbohydrate) or extended fasting. Associated with enhanced mental clarity, fat loss, and neuroprotection.

L-Theanine

An amino acid found naturally in green tea that promotes relaxation without sedation by increasing alpha brainwave activity. Commonly stacked with caffeine to enhance focus while reducing caffeine-induced jitteriness.

Leaky Gut (Intestinal Permeability)

Also: Intestinal hyperpermeability

A condition in which the tight junctions of the intestinal lining become compromised, allowing bacteria, toxins, and undigested food particles to enter the bloodstream. Associated with systemic inflammation, autoimmune conditions, and various chronic diseases.

Lion's Mane Mushroom

A medicinal mushroom (Hericium erinaceus) containing hericenones and erinacines that stimulate Nerve Growth Factor (NGF) synthesis, supporting neuroplasticity, cognitive function, and nerve regeneration. Used as a nootropic and neuroprotectant.

Lymphatic Drainage

Also: MLD, Lymph massage

The lymphatic system — a parallel circulatory network — collects interstitial fluid, immune cells, and cellular waste and returns it to the bloodstream for filtration and excretion. Lymph is moved solely by muscle contraction and breathing (unlike blood, which has the heart). Techniques to support drainage include manual lymphatic drainage (MLD) massage, rebounding (mini-trampoline), dry brushing, cold-hot alternating showers, and compression therapy.

Magnesium

An essential mineral involved in 300+ enzymatic reactions including energy production, protein synthesis, muscle and nerve function, and DNA repair. Highly prevalent deficiency. Biohackers supplement in forms like magnesium glycinate or threonate for sleep, stress, and cognition.

Melatonin

A hormone secreted by the pineal gland in response to darkness that signals the body to prepare for sleep. Commonly used as a sleep supplement (0.5–5 mg) to reset circadian rhythm, reduce jet lag, and ease sleep onset.

Microbiome Diversity

The richness and evenness of microbial species in the gut. Higher diversity is consistently linked to better metabolic health, stronger immunity, reduced inflammation, and lower risk of chronic disease. Diversity is measured by alpha-diversity indices (e.g., Shannon index). Diet variety, fibre intake, and avoiding unnecessary antibiotics are the primary drivers.

Microdosing

The practice of consuming very small, sub-perceptual amounts of psychedelic substances (typically 1/10th to 1/20th of a recreational dose), such as psilocybin or LSD, to enhance creativity, focus, and emotional well-being without inducing a full psychedelic experience.

Milk Thistle (Silymarin)

Also: Silybum marianum, Silymarin

A hepatoprotective herb (Silybum marianum) whose active flavonoid complex silymarin stabilises cell membranes of liver cells, inhibits toxin uptake into hepatocytes, stimulates liver cell regeneration, and upregulates glutathione synthesis. Widely used in integrative medicine for liver disease, alcohol-related liver damage, and medication-induced liver stress.

Mindfulness Meditation

A mental training practice focusing attention on present-moment experience without judgment. Associated with reduced cortisol, improved HRV, enhanced neuroplasticity (increased gray matter density), and reduced inflammation.

Mitochondria

The cellular organelles responsible for producing ATP (adenosine triphosphate) — the cell's primary energy currency — through oxidative phosphorylation. Mitochondrial dysfunction underlies many age-related diseases. Biohackers optimize mitochondrial function through exercise, cold exposure, fasting, and CoQ10.

MTHFR Mutation

A common genetic variant in the MTHFR gene that reduces the enzyme's ability to convert folate to its active form (5-MTHF). Associated with elevated homocysteine, increased cardiovascular risk, and impaired methylation. Often discovered via consumer genetic testing.

mTOR (Mechanistic Target of Rapamycin)

A central cellular signaling pathway that regulates growth, metabolism, and autophagy. mTOR activation promotes anabolism (muscle building); inhibition (by fasting, rapamycin) activates autophagy and is associated with lifespan extension in animal models.

Mycotoxins

Toxic secondary metabolites produced by moulds (primarily Aspergillus, Fusarium, and Penicillium species) that contaminate food crops, water-damaged buildings, and stored grains. Common mycotoxins include aflatoxin B1, ochratoxin A, zearalenone, and trichothecenes. Linked to chronic fatigue, hormonal disruption, neurological symptoms, and immunosuppression. Detected via urine mycotoxin testing.

N-Acetylcysteine (NAC)

Also: NAC, Acetylcysteine

A pharmaceutical-grade precursor to glutathione and a potent mucolytic agent. NAC replenishes intracellular cysteine — the rate-limiting amino acid for glutathione synthesis. Used clinically to treat paracetamol (acetaminophen) overdose, and by biohackers to support liver detoxification, reduce oxidative stress, and break up biofilms.

NAD+ (Nicotinamide Adenine Dinucleotide)

A critical coenzyme involved in cellular energy production, DNA repair, and sirtuin activation. NAD+ levels decline with age. Biohackers supplement with precursors (NMN, NR) to restore NAD+ levels and potentially slow aging.

Neurofeedback

A type of biofeedback using real-time EEG data to train the brain to produce desirable brainwave patterns. Used to treat ADHD, anxiety, PTSD, and optimize peak performance. Consumer EEG devices like Muse make basic neurofeedback accessible.

Neuroplasticity

The brain's ability to reorganize itself by forming new neural connections throughout life. Biohackers target neuroplasticity through learning, exercise, meditation, psychedelic microdosing, and neurofeedback to improve cognitive resilience and performance.

NMN (Nicotinamide Mononucleotide)

A direct precursor to NAD+ that has shown promise in animal studies for reversing aging-related metabolic decline. Popularized by longevity researcher David Sinclair. Human clinical trials are ongoing.

Nootropics

Also: Smart drugs, cognitive enhancers

Substances — natural or synthetic — that claim to enhance cognitive functions such as memory, focus, creativity, or motivation without causing significant side effects. Examples include racetams, lion's mane mushroom, bacopa monnieri, modafinil, and caffeine + L-theanine stacks.

Nutrigenomics

The study of the relationship between nutrition and gene expression. Examines how nutrients influence gene activity and how individual genetic variations affect responses to food. Used to develop personalized nutrition plans based on a person's DNA.

OMAD (One Meal A Day)

An extreme form of intermittent fasting in which all daily calories are consumed in a single meal, resulting in a ~23-hour fasting window. Proponents cite enhanced autophagy, weight loss, and mental clarity.

Omega-3 Fatty Acids

Essential polyunsaturated fats — EPA and DHA (from fish/algae) and ALA (from plants) — critical for brain function, cardiovascular health, and anti-inflammatory pathways. The omega-3:omega-6 ratio is a key biomarker of systemic inflammation.

Open Source Biology

The application of open-source principles to biology — making biological research, tools, and protocols freely available for anyone to use, modify, and distribute. Aims to democratize access to biotechnology and reduce barriers to scientific innovation.

Oura Ring

A smart ring that tracks sleep stages, HRV, body temperature, resting heart rate, and activity. Widely used by biohackers for overnight physiological monitoring and readiness scoring.

Oxidative Stress

An imbalance between reactive oxygen species (free radicals) production and the body's antioxidant defenses, causing cellular damage. A driver of aging and chronic disease. Addressed through antioxidants, reduced inflammation, and mitochondrial optimization.

Peptides (Bioactive Peptides)

Short chains of amino acids that act as signaling molecules in the body. Biohacking peptides include BPC-157 (tissue repair), TB-500 (healing), CJC-1295/Ipamorelin (growth hormone secretion), and Epitalon (telomere support). Many are used off-label and lack human clinical trials.

Phase I Detoxification

Also: CYP450 oxidation

The first stage of liver detoxification, carried out by the cytochrome P450 (CYP450) enzyme family. These enzymes oxidise, reduce, or hydrolyse fat-soluble toxins to prepare them for Phase II conjugation. Phase I can temporarily create reactive intermediates more harmful than the original compound — making Phase II support equally critical.

Phase II Detoxification

Also: Hepatic conjugation

The conjugation stage of liver detoxification in which Phase I metabolites are bound to water-soluble molecules (glucuronic acid, sulfate, glutathione, amino acids) via enzymes such as GSTs, UGTs, and SULTs. This renders toxins water-soluble so they can be excreted via bile or urine. Key nutrients required: glycine, taurine, glutathione, magnesium, B-vitamins.

Polyphasic Sleep

A sleep schedule that divides sleep into multiple shorter periods throughout the day instead of one consolidated nocturnal block. Examples include Uberman (6×20-min naps), Everyman (core sleep + naps), and Dymaxion. Proponents claim it increases productive waking hours.

Postbiotics

Bioactive compounds produced by or released from beneficial bacteria during fermentation, including short-chain fatty acids (SCFAs), enzymes, and peptides. Considered a more stable alternative to probiotics with direct health benefits.

Prebiotics

Non-digestible dietary fibers that selectively feed beneficial gut bacteria, promoting their growth and activity. Examples include inulin, FOS (fructooligosaccharides), and resistant starch found in onions, garlic, asparagus, and green bananas.

Probiotics

Live beneficial bacteria and yeasts that, when consumed in adequate amounts, confer a health benefit on the host. Common strains include Lactobacillus and Bifidobacterium species. Found in fermented foods (yogurt, kefir, sauerkraut) and supplements.

Quantified Self

Also: Self-tracking

A movement and practice of self-tracking biological, physical, and behavioral data using technology to gain self-knowledge and optimize health, productivity, and performance. Also refers to the global community built around this practice.

Quercetin

A flavonoid antioxidant found in onions, capers, and apples with anti-inflammatory, senolytic, and antiviral properties. Used synergistically with dasatinib as a senolytic protocol, and with bromelain to enhance absorption.

Racetams

A class of synthetic nootropics (piracetam, aniracetam, oxiracetam, phenylpiracetam) believed to enhance memory, learning, and neuroprotection by modulating acetylcholine receptors and increasing cerebral blood flow.

Rapamycin

An mTOR inhibitor and immunosuppressant that has extended lifespan in multiple animal models. Increasingly used off-label by longevity-focused biohackers and physicians, despite risks including immunosuppression and metabolic side effects.

Red Light Therapy (Photobiomodulation)

Also: Photobiomodulation (PBM), LLLT

Exposure to red (630–700 nm) and near-infrared (810–850 nm) light to stimulate mitochondrial function via cytochrome c oxidase. Associated with reduced inflammation, improved muscle recovery, skin health, and wound healing.

REM Sleep

Rapid Eye Movement sleep — the stage associated with vivid dreaming, emotional processing, memory consolidation, and creativity. Comprises about 20–25% of total sleep time in adults. REM deprivation impairs learning and emotional regulation.

Resveratrol

A polyphenol found in red wine, grapes, and berries that activates sirtuins and AMPK. Popularized as a longevity molecule by David Sinclair. Evidence in humans is mixed, and bioavailability is enhanced when taken with fat or quercetin.

Sauna (Heat Therapy / Hyperthermia)

Deliberate exposure to high heat (80–100°C in Finnish sauna) as a hormetic stressor. Associated with increased growth hormone, heat shock proteins, cardiovascular conditioning, BDNF production, and reduced all-cause mortality in epidemiological studies.

Senescence

A state in which cells permanently stop dividing but remain metabolically active and secrete inflammatory molecules (the senescence-associated secretory phenotype, SASP). Accumulation of senescent cells drives aging and age-related disease. Senolytics target their elimination.

Senolytics

Compounds that selectively destroy senescent cells, potentially reversing aspects of aging. Examples include dasatinib + quercetin, fisetin, and navitoclax. A rapidly growing area of longevity research and biohacking.

Serotonin

A neurotransmitter regulating mood, appetite, sleep, and social behavior. ~90% is produced in the gut. Levels are influenced by sunlight exposure, exercise, tryptophan intake, and gut microbiome health.

Short-Chain Fatty Acids (SCFAs)

Also: SCFAs

Metabolites produced when gut bacteria ferment dietary fibre, primarily acetate, propionate, and butyrate. SCFAs are the main energy source for colonocytes, reinforce the gut barrier, reduce inflammation, regulate immune responses, and influence brain function via the gut-brain axis.

SIBO (Small Intestinal Bacterial Overgrowth)

Also: Small Intestinal Bacterial Overgrowth

A condition in which bacteria that normally populate the large intestine colonise the small intestine in abnormally high numbers. Causes bloating, gas, abdominal pain, diarrhoea or constipation, and nutrient malabsorption. Diagnosed via breath testing; treated with targeted antibiotics and dietary changes such as a low-FODMAP diet.

Sirtuins

A family of 7 proteins (SIRT1–7) that regulate cellular health, DNA repair, inflammation, and metabolism. Activated by caloric restriction, fasting, and resveratrol. Considered key longevity regulators and targets for anti-aging interventions.

Sleep Architecture

The cyclical pattern of sleep stages — N1 (light sleep), N2 (deeper sleep), N3 (deep/slow-wave sleep), and REM — that repeat throughout the night. Optimizing sleep architecture improves memory consolidation, physical recovery, and hormone regulation.

Sleep Hygiene

A set of behavioral and environmental practices designed to improve sleep quality and duration. Includes consistent sleep schedules, dark/cool bedroom environment, blue light avoidance before bed, and limiting caffeine and alcohol.

Slow-Wave Sleep (SWS)

Also: Deep sleep, delta sleep

The deepest stage of non-REM sleep (N3), characterized by high-amplitude delta brain waves. Critical for physical restoration, immune function, growth hormone secretion, and memory consolidation. Biohackers optimize SWS through temperature (cool room), magnesium supplementation, and avoiding alcohol.

SNP (Single Nucleotide Polymorphism)

A variation in a single nucleotide at a specific position in the genome that differs between individuals. SNPs influence disease risk, drug metabolism, athletic performance, and nutritional needs. Consumer genetics (23andMe, AncestryDNA) identifies thousands of SNPs.

Spermidine

A polyamine found in wheat germ, mushrooms, and aged cheese that potently induces autophagy. Associated with longevity in epidemiological studies. Supplementation is explored as an autophagy activator without the need for fasting.

Synthetic Biology

An interdisciplinary field combining biology, engineering, and computer science to design and construct new biological parts, devices, and systems. Biohackers in DIY labs explore synthetic biology for art, medicine, and biotechnology applications.

Telomeres

Protective caps at the ends of chromosomes that shorten with each cell division. Telomere length is a biomarker of biological aging. Lifestyle factors like exercise, stress reduction, and certain supplements (astragalus/TA-65) are explored to slow telomere attrition.

Testosterone Optimization

Strategies to maintain or increase testosterone levels naturally through sleep optimization, resistance training, zinc and vitamin D supplementation, body fat reduction, and stress management. Medical testosterone replacement therapy (TRT) is a more direct intervention.

Time-Restricted Eating (TRE)

Confining all food intake to a specific daily window (e.g., 8–10 hours) aligned with the body's circadian rhythm. Distinguished from intermittent fasting by its emphasis on meal timing relative to daylight hours.

Toxin Binders

Also: Sequestrants, Gut binders

Substances that adsorb or bind toxins in the gut lumen to prevent enterohepatic recirculation. Categories include: pharmaceutical binders (cholestyramine, welchol), natural binders (activated charcoal, bentonite clay, zeolite, chlorella, modified citrus pectin), and fibre (psyllium, okra). Essential in mould illness/CIRS protocols. Must be taken away from meals and supplements.

Transcranial Direct Current Stimulation (tDCS)

A non-invasive brain stimulation technique that applies a weak direct electrical current (1–2 mA) to specific regions of the scalp to modulate neuronal activity. Used by biohackers to potentially enhance memory, learning, and mood.

Transcranial Magnetic Stimulation (TMS)

A non-invasive procedure using magnetic fields to stimulate nerve cells in the brain. Used clinically for depression treatment; biohackers explore it for cognitive enhancement, neuroplasticity, and mood optimization.

TUDCA

Also: Tauroursodeoxycholic acid

Tauroursodeoxycholic acid — a bile acid produced endogenously in small amounts and available as a supplement. TUDCA promotes bile flow (choleretic effect), protects liver and gut cells from bile-acid-induced apoptosis, and reduces ER stress. Used by biohackers on oral steroid cycles for liver protection and increasingly as a mitochondria-protective and neuroprotective compound.

Vitamin D3 + K2

Vitamin D3 (cholecalciferol) regulates calcium, immune function, and gene expression. K2 (menaquinone) directs calcium to bones and away from arteries. Commonly co-supplemented; deficiency in both is widespread at higher latitudes.

VO2 Max

The maximum rate at which the body can consume oxygen during intense exercise. A key indicator of cardiovascular fitness and a strong predictor of longevity. Can be improved through HIIT, zone 2 training, and altitude training.

Wim Hof Method

A protocol developed by Wim Hof combining breathwork (cyclical hyperventilation), cold exposure, and meditation. Clinical studies have shown it can voluntarily influence the autonomic nervous system and innate immune response.

Xenobiotics

Foreign chemical substances not naturally produced by or expected to be present in the body — including pesticides, industrial pollutants (PCBs, dioxins), pharmaceuticals, food additives, and plasticizers (BPA, phthalates). The liver's Phase I and Phase II enzyme systems are specifically evolved to neutralise and eliminate xenobiotics.

Zone 2 Training

Low-intensity aerobic exercise performed at 60–70% of maximum heart rate, where fat is the primary fuel source. Builds mitochondrial density, improves lactate clearance, and enhances metabolic flexibility. Advocated by longevity researchers like Peter Attia.

Zonulin

A protein that modulates the permeability of tight junctions between intestinal epithelial cells. Elevated zonulin levels signal a compromised gut barrier (leaky gut). Triggered by gluten, gliadin, and lipopolysaccharides from pathogenic bacteria. Serum zonulin is used as a biomarker of intestinal permeability.